The physical environment
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what gases do volcanoes release
Carbon dioxide Methane Water vapour Ammonia Hydrogen sulphide
What gases are is dynamic equilibrium in the atmosphere
Oxygen and Ozone
what happens to the Earth as it cools down from the volcanic eruptions at the start of the atmosphere
As planet cools, water vapour condenses, water settles as ocean. Bacteria live in ocean as the UV rays are too harsh
CO2 percentage in the early atmosphere and now
Early atmosphere = 74% present day = 0.04%
what has the percentage of CO2 changed
dissolved in oceans and formed carbonate rocks
water vapour percentage in the early atmosphere and now
Early atmosphere = 16% now = variable
nitrogen percentage in the early atmosphere and now
Early atmosphere = 3% Now = 78%
hydrogen percentage in the early atmosphere and now
Early atmosphere = 1% now = 0%
oxygen percentage in the early atmosphere and now
early atmosphere = 0% Now = 28%
why has the percentage of water vapour in the atmosphere changed
Condensed and formed oceans
why has the percentage of nitrogen in the atmosphere changed
Activity of bacteria
why has the percentage of hydrogen in the atmosphere changed
escaped from the atmosphere
why has the percentage of oxygen in the atmosphere changed
photosynthesis
daily fluctuations of composition of the atmosphere
CO2 levels fall during the day and increase at night as plants don’t photosynthesise during the night Day = photosynthesis > Respiration Night = Respiration only
yearly fluctuations of composition of the atmosphere
levels fall during summer and increase during Winter Summer = Photosynthesis > Respiration Winter = Respiration > Photosynthesis
why do water vapour levels fluctuate
variable rates of evaporation/evapotranspiration
why do ozone levels fluctuate
variable as a result of equilibrium
negative feedback for an increase in water vapour
increase in cloud cover = decrease in atmospheric pressure = decrease in water vapour
positive feedback for an increase in temperature
decrease in permafrost = increase in decomposition = increase in CO2 and CH4 = increase in temperature
what is proxy data
measure a factor and use it to infer other data
how to use ice cores for proxy data
air bubbles trapped in the ice each winter forms a new layer In Antarctica, drill ice cores with the lower layers representing more years Analyse gas bubbles in each layer - estimate gas concentration use geological signposts like ash from volcanic signposts to date specific years however we cannot be certain of the time.
how to use carbon dating for proxy data
living organisms take in C14 After death, C14 converts back to C12 at a predictable rate Analyse rate of C14 to C12 If C14 < C12 then its older peat bogs and lake sediments are good areas of no O2
carbon dating - pollen
different plants produce different shades = we can see what plant was growing at the time as to use it to learn about the conditions were at the time
how to use oxygen isotopes for proxy data
oxygen analysis in seawater, polar ice, calcite proportion of O18 - O16 changes in hot/cold years increase O18 = cold year decrease in O18 = warm year calcite = sedimentary mineral in the ocean floor Mg:Ca = magnesium deposition = warmer year